They are rougly every 2 hours during the holiday season.
From Fethiye: 07.00 - 11.00 - 17.00 (APRIL - MAY )
From Kabak : 08:30 -12:30 - 18 :30 ( APRIL - MAY )
From Fethiye : 07:00-09:00 -11:00 - 13:00 - 16:00 - 18:00 ( JUNE - JULY - AUGUST)
From Kabak : 08:30 - 10:30 -12:30 - 14 :30 - 17 : 30 - 19 :30 ( JUNE - JULY - AUGUST )
You can catch them between Fethiye and Oludeniz Terminus. The fare last year was 6TL from Fethiye and 4TL from Oludeniz. I'm not sure what it'll be this year.
( If you're a nervous passenger sit on the driver's side.

))